DIY cat deterrent spray Even if you've purchased scratching posts for your kitty, he may not always want to make full use of it. (petsmagazine.com.sg)
There are also a variety of ultrasonic cat deterrents available, which use a harmless burst of ultrasonic sound to keep cats out of the area. (catsandbirds.ca)
SpraySentry ™ Cat Deterrent System This is a device that detects movement within several feet and delivers a short burst of compressed air to deter the cat. (petenrichments.com)